1. Field of the Invention
The present invention relates to a dispensing apparatus for a liquid crystal display panel, and more particularly, to a complex dispensing apparatus capable of simplifying fabrication processes by forming of silver paste and sealant with one complex line and a dispensing method for a liquid crystal display panel using the same.
2. Discussion of the Related Art
In the recent information oriented society, importance of visual display devices has increased. Requirements for better display devices having low power consumption, thin thickness, light weight and high picture quality have to be satisfied. Because the characteristics of LCD (liquid crystal display) devices satisfy all those conditions and are suitable for mass-production, various new LCD products have been rapidly developed. LCD devices have become the core industry gradually replacing the conventional CRT (cathode ray tube) devices.
In general, the liquid crystal display devices display a picture by adjusting a light transmittance ratio of liquid crystal cells by respectively supplying a data signal according to picture information to the liquid crystal cells arranged as a matrix form.
Generally, the liquid crystal display devices include a liquid crystal display panel having a driving circuit unit in order to output pictures, a backlight unit installed at the lower portion of the liquid crystal display panel to emit light to the liquid crystal display panel, and a chassis, etc. for combining and supporting the backlight unit and the liquid crystal display panel.
Hereinafter, the liquid crystal display panel will be described in detail with reference to FIG. 1.
FIG. 1 is a schematic plan view illustrating a structure of a related art liquid crystal display panel.
In FIG. 1, the liquid crystal display panel largely includes of an array substrate 20 having a driving circuit unit (not shown), a color filter substrate 30, and a liquid crystal layer (not shown) formed between the array substrate 20 and the color filter substrate 30.
Herein, on the array substrate 20, a plurality of gate lines 21 and data lines 22 are arranged lengthwise and breadthwise, respectively, on the substrate 20 to define a plurality of pixel regions. In addition, a TFT (thin film transistor) (not shown) is formed at each crossing of a gate line 21 and a data line 22, and a pixel electrode (not shown) is formed at each pixel region.
In addition, a certain portion (consisting of a shorter side and a longer side) of the array substrate 20 extends beyond the respective sides of the color filter substrate 30 to allow for the formation of the driving circuit unit for driving the liquid crystal display panel. In particular, a gate pad unit 24 is formed at the extended shorter side of the array substrate 20, and a data pad unit 23 is formed at the extended longer side of the array substrate 20.
Herein, the gate pad unit 24 supplies a scanning signal from a gate driving circuit unit (not shown) to the gate line 21 of each pixel region as a picture display region 25, and the data pad unit 23 supplies picture information from a data driving circuit (not shown) to the data line 22 of each pixel region.
In the meantime, a color filter (not shown) for implementing color and a common electrode (not shown) as an opposed electrode of the pixel electrode formed on the array substrate 20 is formed in the picture display region of the color filter substrate 30.
A cell gap is formed between the array substrate 20 and the color filter substrate 30 using a spacer (not shown) to separate the substrates uniformly, and they are attached by a seal pattern 40 formed at the edge of the picture display region 25. Accordingly, a unit liquid crystal display panel is obtained. The two substrates 20, 30 are attached using an alignment key (not shown) formed at the array substrate 20 or the color filter substrate 30.
In order to fabricate the above-mentioned liquid crystal display panel, in particular, in order to attach the array substrate to the color filter substrate, a process for forming a seal pattern on the edge of the picture display region is required, and a general seal pattern forming method will be described in detail with reference to accompanying drawings.
First, FIGS. 2A and 2B are exemplary views illustrating forming a seal pattern by a general screen-printing method.
As depicted in FIGS. 2A and 2B, a screen mask 50 is patterned to expose a plurality of seal patterns 40A-40C forming regions selectively and a rubber squeegee 55 is used for forming the plurality of seal patterns 40A-40C simultaneously by selectively supplying a sealant 70 to the substrate 10 through the screen mask 50.
The plurality of seal patterns 40A-40C formed on the substrate 10 provide a gap in which a liquid crystal layer (not shown) is formed and prevent liquid crystal from being leaked from picture display regions 25A-25C.
Accordingly, the plural seal patterns 40A-40C are formed along the edge of the picture display regions 25A-25C, and liquid crystal injection holes 45A-45C are formed at a side of the seal patterns 40A-45A respectively.
The above-mentioned screen-printing method includes forming a plurality of seal patterns 40A-40C on the substrate 10 by coating sealant 70 onto the screen mask 50 on which the plurality of seal patterns forming regions are patterned and printing the seal patterns 40A-40C by applying the rubber squeegee 55 and drying the seal patterns 40A-40C for leveling by evaporating a solvent contained in the plurality of seal patterns 40A-40C.
Because of the convenient processing advantage, the screen-printing method is generally used. However, forming the plurality of seal patterns 40A-40C by coating the sealant 70 on the entire surface of the screen mask 50 and printing it with the rubber squeegee 55 causes a large amount of sealant 70 to be consumed.
In addition, the contact of the screen mask 50 and the substrate 10 may cause an alignment layer (not shown) formed on the substrate 10 to have a rubbing defect, and accordingly picture quality of the liquid crystal display devices may be reduced.
Accordingly, in order to solve the problem of the screen-printing method, a seal dispensing method has been presented.
FIG. 3 is an exemplary view illustrating forming a seal pattern by a related art seal dispensing method. In FIG. 3, a sealant is discharged by applying a uniform pressure to a plurality of syringes (180A-180C) arranged fixed at a support rod 185 while a table 115 on which a substrate 110 is loaded is moved front and rear (and right and left). Thus, a plurality of seal patterns 140A-140C are formed along the edge of picture display regions 125A-125C of the substrate 110.
In the seal dispensing method, by selectively supplying a sealant only to the edge of the picture display regions 125A-125C of the substrate 110, the amount of the sealant consumed can be reduced. In addition, because the plurality of syringes 180A-180C do not contact the picture display regions 125A-125C of the substrate 110, rubbing inferiority of an alignment layer (not shown) can be prevented. Accordingly, picture quality of a liquid crystal display can be improved.
However, the seal dispensing method cannot efficiently accommodate substrates having increased area or picture display regions having different areas (125A-125C) formed on the substrate 110, which may result from a change in the model or type of a liquid crystal display panel being manufactured.
In more detail, a recent trend to liquid crystal display panel having a large area, the area of the substrate 110 for fabricating a large-sized liquid crystal display panel is increased. Accordingly forming positions of the seal patterns 140A-140C are changed on the substrate 110. In the above-mentioned seal dispensing method, when forming positions of the seal patterns 140-140C are changed, the dispensing apparatus has to be reconstructed by disassembling and reassembling the support rod 185 and the syringes 180A-180C.
When a model of the liquid crystal display panel is changed, an area of the picture display regions 125A-125C formed on the substrate 110 is changed, and accordingly positions of the seal patterns formed at the edge of the picture display region 125A-125C are changed. In the seal dispensing method, when positions of the seal patterns 140A-140C are changed, by disassembling and re-assembling the support rod 185 and the syringes 108A-180C, the dispensing apparatus has to be reconstructed.
Accordingly, man-power is required, a time required for processing is increased, and, accordingly, productivity may be lowered.
In the meantime, either before or after the seal dispensing step, a silver dot is formed on the array substrate or the color filter substrate. Hereinafter, the silver dot will be described with reference to accompanying drawings.
FIG. 4 is a schematic sectional view illustrating the edge of the liquid crystal display panel in FIG. 1.
In FIG. 4, an array substrate 120 and a color filter substrate 130 face each other and are attached so as to have a certain gap by a spacer 155 and a seal pattern 140, and a liquid crystal layer 160 is formed in the gap between the array substrate 120 and the color filter substrate 130.
Herein, not shown in FIG. 4, a gate line to which a scanning signal is applied through a gate pad unit and a data line to which picture information is applied through a data pad unit are arranged so as to cross each other in a picture display region of the array substrate 120, and a TFT (thin film transistor) for switching a liquid crystal cell and a pixel electrode contacted to the TFT are formed in the crossing region.
In addition, a color filter (not shown) divided-coated by cell regions by a black matrix (not shown) and a common electrode 138 for driving a liquid crystal layer 160 with a pixel electrode formed on the array substrate 120 are formed in a picture display region of the color filter substrate 130.
Herein, a common voltage wiring 139 for applying a common voltage to a common electrode 138 on the color filter substrate 130 is formed on the array substrate 120, and the common voltage wiring 139 and the common electrode 138 are electrically connected through a silver dot 190 formed on the array substrate 120 or the color filter substrate 130.
In the meantime, because the silver dot and the seal pattern are formed in different processing steps by using different dispensing apparatus, a time required for the entire processing is increased, and accordingly productivity may be lowered.
In particular, in case of performing the general processing even in fabrication of liquid crystal display devices not requiring the silver dot forming process (for example, IPS (in-plane switching) liquid crystal display devices), efficiency related to facility usage and fabrication time may be lowered.